lsst.pipe.drivers.checksum Namespace Reference

Functions
def	checksum (obj, header=None, sumType="MD5")
	Calculate a checksum of an object. More...

Variables
tuple	exposureTypes = (afwImage.ExposureF, afwImage.ExposureD,)
tuple	maskedImageTypes = (afwImage.MaskedImageF, afwImage.MaskedImageD,)
tuple	decoratedImageTypes = (afwImage.DecoratedImageF, afwImage.DecoratedImageD,)
tuple	imageTypes = (afwImage.ImageF, afwImage.ImageD, afwImage.ImageI,)
int	PROTOCOL = 2
dictionary	sumFunctions

Function Documentation

checksum()

def lsst.pipe.drivers.checksum.checksum	(		obj,
			header = None,
			sumType = "MD5"
	)

Calculate a checksum of an object.

We have special handling for images (e.g., breaking a MaskedImage into its various components), but the object may be any picklable type.

Parameters

obj	Object for which to calculate the checksum
header	FITS header (PropertyList) to update with checksum values, or None
sumType	Type of checksum to calculate

Returns

dict with header keyword,value pairs

Definition at line 24 of file checksum.py.

def checksum(obj, header=None, sumType="MD5"):
    """!Calculate a checksum of an object
 
    We have special handling for images (e.g., breaking a MaskedImage into
    its various components), but the object may be any picklable type.
 
    @param obj  Object for which to calculate the checksum
    @param header  FITS header (PropertyList) to update with checksum values, or None
    @param sumType  Type of checksum to calculate
    @return dict with header keyword,value pairs
    """
    assert sumType in sumFunctions, "Unknown sumType: %s" % (sumType,)
    func = sumFunctions[sumType]
 
    results = {}
 
    if isinstance(obj, exposureTypes):
        obj = obj.getMaskedImage()
    if isinstance(obj, decoratedImageTypes):
        obj = obj.getImage()
 
    if isinstance(obj, maskedImageTypes):
        results[sumType + "_IMAGE"] = func(obj.getImage())
        results[sumType + "_MASK"] = func(obj.getMask())
        results[sumType + "_VARIANCE"] = func(obj.getVariance())
    elif isinstance(obj, imageTypes):
        results[sumType + "_IMAGE"] = func(obj)
    else:
        results[sumType] = func(obj)
 
    if header is not None:
        for k, v in results.items():
            header.add(k, v)
 
    return results

Variable Documentation

decoratedImageTypes

tuple lsst.pipe.drivers.checksum.decoratedImageTypes = (afwImage.DecoratedImageF, afwImage.DecoratedImageD,)

Definition at line 12 of file checksum.py.

exposureTypes

tuple lsst.pipe.drivers.checksum.exposureTypes = (afwImage.ExposureF, afwImage.ExposureD,)

Definition at line 10 of file checksum.py.

imageTypes

tuple lsst.pipe.drivers.checksum.imageTypes = (afwImage.ImageF, afwImage.ImageD, afwImage.ImageI,)

Definition at line 13 of file checksum.py.

maskedImageTypes

tuple lsst.pipe.drivers.checksum.maskedImageTypes = (afwImage.MaskedImageF, afwImage.MaskedImageD,)

Definition at line 11 of file checksum.py.

PROTOCOL

int lsst.pipe.drivers.checksum.PROTOCOL = 2

Definition at line 15 of file checksum.py.

sumFunctions

dictionary lsst.pipe.drivers.checksum.sumFunctions

Initial value:

=  {
    "CRC32": lambda obj: zlib.crc32(pickle.dumps(obj, PROTOCOL)),
    "MD5": lambda obj: hashlib.md5(pickle.dumps(obj, PROTOCOL)).hexdigest(),
}

Definition at line 18 of file checksum.py.